MAINTENANCE OF IONS, PROTEINS AND WATER IN LENS FIBER CELLS BEFORE AND AFTER TREATMENT WITH NONIONIC DETERGENTS

If the plasma membrane and its associated transport proteins are solel y responsible for maintenance of the asymmetric solute distribution th en disruption of the plasma membrane would quickly lead to the symmetr ic distribution of all unattached inorganic ions between the cell and the extracellular environment. To test this hypothesis fresh pig lense s were incubated in Hanks' balanced salt solution in either absence or presence of non-ionic detergents (0.2% Triton X-100 or 0.2% Brij 58). Both detergents caused permeabilization of every lens fiber cell as s hown by electron microscopy. The flux kinetics of K+, Mg2+, Na+, Ca2+, water and protein out of and into the permeabilized lens fiber cells was measured. Triton X-100 caused a faster flux rate of all solutes th an did Brij 58. The Triton X-100 induced flux of solutes and water was associated with a decrease in lens ATP. Incubation of untreated lense s in solutions of different osmotic pressures at 0 degrees C demonstra ted that the major fraction of lens water was osmotically unresponsive . Thus the asymmetric distribution of solutes in lens fiber cells is d ependent on an intact plasma membrane and on a co-operative ATP-depend ent association between K+, Mg2+, water and cytomatrix proteins. (C) 1 996 Academic Press Limited